Anhydrid of acyl salicylic acid.



FRITZ HOFMANN, OF ELBERFELD, GERMANY, ASSIGNOR TO FARBENFABRIKEN VORM.FRIEDR. BAYER & 00., OF ELBEBFELD', GERMANY, A CORPORATION OF GERMANY.

nnirn ,sras m ANHYDRID OF AGYL SALICYLIC ACID.

Specification of Letters-Patent. Patented May 25, 190% Application.filed Gctcbcr 31, 1907. Serial No. 399,991

and stirred. The reaction begins at once, carbonic acid being evolvedand pyridin hydrochloridbeing precipitated. When the re To all whom itmay concern:

Be it known that I, FRITZ HOFMANN, doctor of philosophy, chemist,citizen of the German Empire, residing at Elberfeld, Ger many, Kingdomof Prussia, have invented new and useful Improvements in Anhydrids ofAcyl Salicylic Acids, of which the following is a specification.

This invention relates to the manufacture and production of the hithertounknown anhydrids of acyl-salicylic acids having most probably thefollowing general formula:

acid are added and the mixtureis well agitated in a separating funnel;The aqueous layer containing the pyridin hydrochlorid is separated fromthe benzene solution and the latter is water bath and the residue isextracted with 500 parts of warm ether (free from alcohol action iscomplete ice and dilute'hydrochloric I dried over granular chlorid otcalcium; the benzene is then distilled of? m vacuo on the /OR andwater). On cooling the new anhydrid 7 x of acetyl salicylic acid havingprobably the formula: o.coori, C5H4\ a 4 0R oo (R meaning an acylradical). v

These new products are valuable theraneutic compounds. They aretasteless and non-irritant and surpass in this respect even the acetylsalicylic acid frequently administercd as a substitute for salicylicacid. Acetyl salicylic acid has a marked acid taste fOnOWmg formula:

crystallizcs'h'om the ether. It is filtered oil and dried at from to C.lts formawhich is disag eeable to many patients and l (a H o.cocs.,furthermore it may produce unpleasant re- \COOH a sults in case ofabnormal sensitiveness oi the -n mucous membranes of the stomach. The n/5 oooon ococn8 new compounds do not suffer from these disadvantages andhave proved to be valuable remedies for influenza, rheumatic or otherdiseases in which salicylic acid is administered. They are to beprescribed or taken in similar doses as sodium salicylate or acetylsalicylic acid.

The process for producing the new compounds consists in treatingacyl-sahcyhc acids with phosgen in the presence of tertiary bases; 6. gpyridin.

The new products are white neutral compounds which do not give withferric chlor d the violet coloration characteristic of sallcylic The newcompound forms white crystals melting at 82 to 83 C. and after repeatedcrystallization from alcohol at 85 C. It is tasteless and of neutralreaction, soluble with difficulty in ether and scarcely soluble inwater, soluble in hot alcohol and easily soluble in acetone. On boilingit with an excess of caustic soda lye it is decomposed, salicylic acidbeing formed.

The other anhydrids of acyl salicylic acids are )roduced in an analogousmanner.

The anhydrid of carboxethyl salicylic acid acid. They are soluble in hotalcoholand o6H., z: scarcely soluble in water. 011 boiling the anhydridsfor some time with pausticdalianes d al'c ic aci eing ocooo u they aredecompose s 1 y melts at M C. I

formed.

In order to illustrate my inventionl give the/following example, partsbeing by weight: 158 parts of pyridin are added toa solution of 360parts of acetyl salicylic acid in 500 parts of benzene, and a solutionof 99 narts of phosgen in 500 parts of benzene is then added to thismixture while 1t 18 cooled The anhydrid of benzoylsalicylic acid oooonO6H4 r 5 co tion tal ies probably place according to the melts at114-116 .C.

Having now described my invention and in what manner the same is to beperformed, what claim as new and desire to LettersvPatent is y f1.Theherein-described new anhydrids, of

acyl salicylic acids obtainable by the action of phosgen and pyridinupon acyl salicylic acids which are White crystalline neutral com oundssoluble in hot alcoholfscarcely 'solu l'e-in water and do not give theviolet coloration with ferric chlorid; which by heating with causticalkalies are decom osed salicylic acid being formed and eXhi itingvaluable therapeutic properties, substantially as hereinbeforedescribed.

secure by 2. ,The herein-described new'anhyd rid" of acetyl salicylicacidhaving probably the above formula, obtainable bylthe action ofphosgen and pyridin' upon 'acet'yl'salicylic acid, and being a whitecrystallinef'neutral compound melting at 85 C. after recstalllZMZlOIlfIOIIl alcohol, being easily solu lein acetone, soluble inhot alcohol, soluble with difliculty in ether and being scarcely solublein water and not givin the violet coloration with ferric ,chlorid, saicylic acid being relye; and exhibiting valuable therapeutic properties,substantially as hereinbefore de scri ed.

In testimony whereof I have hereunto set my hand in the presence of twosubscribing witnesses. FRITZ -HOFMANN. [L. s.]- Witnesses: 1

. OTTO KoNie, 7

WM. WASHINGTON BRUNSWICK.

7 generated by heating it with caustic soda

